A sequence detector generally comprises circuitry operative to receive an incoming stream of bits and to indicate, almost in real time, when those bits take on a certain predetermined property. Sequence detectors may be utilized, for example, to generate a signal (e.g., a logical high) every time a particular sequence of bits (e.g., 10101) occurs in an incoming bit stream. A particular sequence of bits may be included, for instance, at the beginning and end of a digital message. A sequence detector may be a useful tool in signaling the beginning and end of such a message.
Sequence detectors tend to need greater memory reserves when the number of bits in the sequence being detected is large. Greater memory reserves, in turn, tend to make sequence detection circuitry larger and ultimately more expensive to implement.